Back in the administration of W., we looked for the weapons of mass destruction in Iraq. That was the wrong place; they’re here at home. Normally the W.M.D. I write about is the Standard American Diet (yes: SAD); occasionally I talk about food safety, or climate change, or related topics. But no matter what you look at, the basic problem remains so-called leadership that cannot stand up to big ag, big food, big energy, Wall Street …or the N.R.A.

Since 9/11, 33 Americans have been killed by “terrorists”; roughly 150,000 Americans have been killed by non-terrorists: that is, your run-of-the-mill murderers. Murder, like the leading cause of death — heart disease — is often preventable, through regulations, education and medical intervention.

We don’t know why Jared Loughner — had you, too, forgotten his name before he reappeared in the news on Tuesday? — shot Gabby Giffords, but we do know that he told his shrink that he wished he’d taken the antidepressants he’d been prescribed before the shooting. We don’t know why James Holmes allegedly shot up the Batman crowd, but we do know he was acting in a weird manner, and though his analyst told the police he was troubled, there was no one to help him. We gather that the suicidal Wade M. Page was a racist so ignorant he didn’t know a Sikh from a Muslim.

In any event, none of them seem to have been capable of distinguishing right from wrong. The easy solution to that is to make gun purchases more difficult, especially for disturbed people who appear to think they’re part of some “solution” to a series of “problems” identified by hatemongers. (Remember Bill O’Reilly all but calling for the death of the “baby killer,” the obstetrician George Tiller?)

We already have laws and regulations to protect us from murderers, at least when we call them terrorists. We have our mouthwash and water confiscated, we take our shoes off, we’re bombarded by X-rays and herded like cattle, photographed and eavesdropped upon. If a Muslim had flown a small plane into a movie theater, do you doubt that stricter laws governing the use of private planes would have followed? Yet you can buy a semiautomatic weapon online almost as easily as you can a book.

Yes, no law is going to stop a crime of passion, but crimes of passion don’t kill people by the dozens; neither do knives or rifles. The opponents of gun control, like those of many progressive measures, spread doubt: “Gun control might not have prevented Aurora,” they say, or, nuttily, “If someone in that theater had been packing, they could’ve taken Holmes out.”

Similar statements that stall forward movement: “How do you know climate change is responsible for this drought?” “Processed food didn’t create the obesity epidemic; overeating and lack of exercise did.” “Our food supply is already the safest in the world.” “Financial regulation may slow the economy.”

It’s easy to say that without proof of direct causation you can’t justify regulation, but how many people died while the tobacco companies lied? Of course cause and effect is complex, but that’s no reason to ignore the smokiest guns.

This is where leadership comes in; you read President Obama’s statements after Aurora and Oak Creek, and each is nearly identical to the other, and for that matter to Mitt Romney’s.

Yes, we’re all sad; but real leaders lead. Though gun control is said to be too risky an issue for most politicians, didn’t we elect them for their judgment and will? Otherwise, why not govern by polls and Twitter?

I suppose it goes without saying, but United States gun regulation is lax. Perhaps not generally as lax as it is in Arizona, where, says the F.B.I. agent Dave Voth (quoted in Fortune), “someone buying three guns is like someone buying a sandwich,” but lax enough so that we collectively own 300 million guns, more than there are adults in this country. (Even more than there are cars, and you know how we are about cars.) And despite Mitt Romney’s misstatements, most weapons used in murders, even semiautomatics, are bought legally — including the weapons of Mr. Loughner, Mr. Holmes and Mr. Page. In the United States, there are nearly three (2.98) gun murders per 100,000 people. In Britain, by contrast, where there were 18 gun homicides in 2009 (a rate of nearly zero — actually 0.03 — per 100,000 people), civilians can’t even possess pistols or revolvers. And there are records of gun acquisitions, sales and transfers.

We’ve experimented with little or no gun control. It doesn’t work. Let’s try something else: real gun control. That will work; after all, it was law enforcement officials and unarmed citizens — not vigilantes — who apprehended Mr. Loughner, Mr. Holmes and Mr. Page. Then perhaps we’ll be encouraged to move in better directions on other issues we need to tackle: Health care. Diet. Climate change. Our lives ride on all of these.